Antarctic Peninsula warm winters influenced by Tasman Sea temperatures

Kazutoshi Sato,Ian Simmonds,Jun Inoue,Irina Rudeva

doi:10.1038/s41467-021-21773-5

Abstract

The Antarctic Peninsula of West Antarctica was one of the most rapidly warming regions on the Earth during the second half of the 20th century. Changes in the atmospheric circulation associated with remote tropical climate variabilities have been considered as leading drivers of the change in surface conditions in the region. However, the impacts of climate variabilities over the mid-latitudes of the Southern Hemisphere on this Antarctic warming have yet to be quantified. Here, through observation analysis and model experiments, we reveal that increases in winter sea surface temperature (SST) in the Tasman Sea modify Southern Ocean storm tracks. This, in turn, induces warming over the Antarctic Peninsula via planetary waves triggered in the Tasman Sea. We show that atmospheric response to SST warming over the Tasman Sea, even in the absence of anomalous tropical SST forcing, deepens the Amundsen Sea Low, leading to warm advection over the Antarctic Peninsula.

Highlights

The Antarctic Peninsula of West Antarctica was one of the most rapidly warming regions on the Earth during the second half of the 20th century
Weak negative trends of Antarctic Peninsula (AP) air temperature since 1999 were reported by a previous study[10], our analysis shows that the AP stations experienced eight warm winters since that time
In summary, we have shown that warm winter episodes in the Tasman Sea influence warm temperature anomalies over key regions of West Antarctica, including the AP, through a poleward shift of South Pacific cyclone tracks

Summary

Introduction

The Antarctic Peninsula of West Antarctica was one of the most rapidly warming regions on the Earth during the second half of the 20th century. The increases in air temperature over Antarctica are related to enhanced warm advection associated with changes in the key atmospheric circulations over the Southern Ocean (SO) (e.g., the Amundsen Sea Low [ASL]12–16 and the Southern Annular Mode [SAM]17–21). In the austral cold seasons, heating by anomalous sea surface temperatures (SSTs) in the tropical region generates a Rossby wave train from the tropics to the Antarctic region via the SO, influencing its teleconections[8,9,22,23,24] By this mechanism, the El Niño-Southern Oscillation (ENSO) modulates the position and strength of the ASL16,22,23,25,26. We investigate the linkage between ocean variabilities in the Southern Hemisphere mid-latitudes and Antarctic warming using reanalysis datasets and an atmospheric general circulation model. Our model experiments show that the increase in SST in the Tasman Sea alone produces warming in the AP even without anomalous tropical SST cooling

Methods

Results

Conclusion